This invention relates to high speed dental drill-type tools, and more particularly to a high speed dental drill-type tool having a self-tightening chuck, which self-tightens during operational use of the dental drill-type tool, and which eliminates the necessity for very strong or powerful manual pre-tightening of the chuck holding the working tool before beginning a dental operation.
In the prior art, when practitioners use a dental drill-type tool (hereafter referred to as a dental drill) providing rotary drive to a working tool, such as a drill bit, the working tool is coupled to the rotary drive or turbine member of the drill by means of a chuck which is tightened manually before use. Thus, an extra operation of tightening the chuck with a small tightening tool, which is easily misplaced, is required. Moreover, if the chuck in the prior art is inadvertently not tightened before use, or is not tightened sufficiently (i.e., the tightening force is not strong or powerful enough), there is a possibility of the tool flying out of the drill during start-up or during operation, thereby creating a danger to the patient and/or to the practitioner, and possibly causing damage to the drill mechanism or other nearby objects.
Still further, in the prior art dental drill tools, when the tool is operated in the mouth of a patient, if too much force is applied to the working tool during use, for example by pressing too hard on a tooth or mouth structure of the patient, the rotation of the turbine of the drill tends to be slowed down, and the reaction forces are such as to loosen the conventionally-used right-hand threaded tool holding chucks, thereby creating a danger that the tool may fly out of the chuck and injure the patient, or that the upper screw-threaded member of the conventional chuck (see FIG. 2) may unthread and move upwardly in the direction of arrow A (FIG. 2) within the drill housing and jam against an upper cover thereof, thereby damaging the internal mechanism of the dental drive tool.
The object of the present invention is to provide a dental drill drive tool having a self-tightening chuck which is easy to use, which is self-tightening at the beginning of use, which self-tightens during use, and which eliminates the disadvantages of the prior art chuck mentioned above.